It is known that problems are encountered in using satellite communication devices in mountainous areas where a view of the sky can be blocked to where the satellites are located as they move across the sky.
This is particularly applicable to low-earth orbit satellite communication systems, including Orbcomm, Iridium and Globalstar, where the satellites change position relative to observers on the ground. Thus, even though a satellite is expected to be in view above the horizon, it is in fact blocked due to the presence of a mountain in the direction concerned.
This can lead to many failed communication attempts which are inconvenient and more importantly use significant power leading to drain on portable equipment where the power supply is a significant part of the weight and volume of the equipment.